Extensions to BGP-LS for Advertising IFIT Node Capability

IFIT provides a complete framework architecture and a reflection-loop working solution for on-path flow telemetry . At present, there are a family of emerging on-path flow telemetry techniques, including In-situ OAM (IOAM) , PBT , IOAM Direct Export (DEX) , Enhanced Alternate Marking (EAM) , etc. IFIT is a solution focusing on network domains. The "network domain" consists of a set of network devices or entities within a single administration. For example, a network domain can be one or more IGP routing domains. The family of emerging on-path flow telemetry techniques may be selectively or partially implemented in different vendors' devices as an emerging feature for various use cases of application-aware network operations. Hence, in order to enable IFIT applications in an operational network domain, IFIT node capabilities SHOULD be advertised by every Intermediate System to Intermediate System (IS-IS) router in the network domain. BGP-LS defines a way to advertise topology and associated attributes and capabilities of the nodes in that topology to a centralized controller . This document defines extensions to BGP-LS to advertise the IFIT node capabilities to BGP-LS consumers.

BGP-LS: Advertisement of Link-State and TE Information using Border Gateway Protocol

IFIT is expected to be deployed in a specific domain referred as the IFIT domain. An IFIT domain may cross multiple network domains. One network domain may consists of multiple IFIT domain. Within the IFIT domain, the IFIT data fields of flow information head MAY be updated by network nodes that the packet traverses.

Each IFIT node is configured with a node-id which uniquely identifies a node within the associated IFIT domain. To accommodate the different use cases or requirements of in-situ flow information telemetry, IFIT data fields updated by network nodes fall into different categories which are referred as different IFIT option types, including IOAM Trace Option-Types , IOAM Edge-to-Edge (E2E) Option-Type , IOAM DEX Option-Type and Enhanced Alternate Marking (EAM) Option-Type . So IFIT Option Types SHOULD be carried in IFIT node capability advertisment.

This document describes extensions enabling BGP-LS speakers to announce the IFIT node capabilities of routers in a network to a BGP-LS consumer (e.g. a centralized controller). The centralized controller can leverage this information in enabling IFIT applications in network domains based on IFIT node capabilities and OAM use cases.

IFIT Node-Capability TLV is defined as a new Node Attribute TLV that is encoded in the BGP-LS attribute with Node NLRIs . The IFIT Node Capability TLV is defined as a TLV triplet, i.e. a two-octet Type field, a two-octet Length field, and 4-octet Value field. The Type field indicates the type of items in the Value field. The Length field indicates the length of the Value field in octets. The Value field indicates the IFIT Node Capability, which is a 4-octet IFIT Option Type-enabled Flag bitmap. The IFIT Node capability TLV has the following format:

Type: To be assigned by IANA Length: A 8-bit field that indicates the length of the value portion in octets and will be a multiple of 4 octets dependent on the number of capabilities advertised. IFIT Option Type-enabled Flag: A 4-octet field, which is defined as following:

Where: p-Flag: IOAM Pre-allocated Trace Option Type-enabled flag. If p bit is set (1), the router is capable of IOAM Pre-allocated Trace . i-Flag: IOAM Incremental Trace Option Type-enabled flag. If i bit is set (1), the router is capable of IOAM Incremental Tracing . d-Flag: IOAM DEX Option Type-enabled flag. If d bit is set (1), the router is capable of IOAM DEX . e-Flag: IOAM E2E Option Type-enabled flag. If e bit is set (1), the router is capable of IOAM E2E processing . m-Flag: Enhanced Alternative Marking enabled flag. If m bit is set (1), then the router is capable of processing Enhanced Alternative Marking packets . Reserved: Must be set to zero upon transmission and ignored upon receipt. An IFIT node SHALL be capable of more than one IFIT option types. So in this case, IFIT Option Type-enabled Flag bitmap SHOULD has more than one bit being set.

Note to RFC Editor: this section may be removed on publication as an RFC.

This document makes the following registrations for a Node Attribute TLV code point for the IFIT Node Capability TLV included with Node NLRIs. Code Point Description TBD IFIT Node Capability

This document introduces new Node Attribute TLVs for the existing Node NLRIs. It does not introduce any new security risks to BGP-LS.